Power transmission



Aug.6, 1940. R052 2,210,129

POWER TRANSMISSION Filed Dec. 15, 1936 2 Sheets-Sheet 1 INVENTOR [Du/0v LJEos:

WLW

ATTORNEY 8- 6, 1940- E. 1.. ROSE 2.210,!29

POWER TRANSMISSION Filed Dec. 15,1936 2 Sheets-Sheet 2 "20 a 60 sa 3.94/ a? 44 67 7 11- -2 5 INVENTOR EON/n L. 19055 BY W T w ATTORNEY Patented Aug. 6, 1940 POWER TRANSMISSION v Edwin L. Rose, Watertown, Conn., assignor to The Waterbury Tool Company, Waterbury, Conn., a corporation of Connecticut Application December 15, 1936, Serial'No. 115,991

17 Claims.

This invention relates to power transmissions,

1 wherein each of the fluid motors may be indeto the motor.

There are many examples of power transmisr sion installations in which a large number of independent machine units or sections of a machine are driven from a common source of power, as for example in a factory. It is necessary that each unit be capable of control as to speed independently of all the other. units. In many instances, it is desirable to provide some means for varying the speed of the machine unit smoothly over a considerable range.

Hydraulic power transmission devices afford a ready means of providing smoothly variable speeds; that is without steps, but heretofore have required a complete individual pump and motor transmission unit for each machine unit being driven. It is well known that if a plurality of fluid motors be connected in parallel to a common pump that the fluid, following the path of least resistance, will operate only that motor which has the least resisting load so that it is impossible to insure driving two or more motors at different speeds or loads. Likewise, if the motors be connected in series to a common pump,

equally great practical d'ifliculties are encountered since it is necessary to operate the common pump against a pressure head equal to the sum of the pressures across each motor, and if any 40'considerable number of motors are used, the

pump pressure becomes excessive or if this is to be avoided, the size of the motor required is Further objects and advantages of the present invention will be apparent from the following 55 description, reference being had to the accompendently controlled and regulated as to speed I regardless of variations in the torque load applied I drives-an independent load device indicated diapanying drawings wherein a preferred form of the present invention is clearly shown.

In the drawings; Fig. 1 is a diagrammatic view of a powe transmission system incorporating a preferred form'of the present invention.

Fig. 2 is a side view partly in section of a fluid motor and control mechanism forming one of the elements of the system of Fig. 1.

Fig. 3 is a cross section on line 3-3 of Fig. 2'.

Fig. 4 is a fragmentary cross section on line |4 of Fig. 3. 1

Referring now to Fig. 1 there is illustrated a source of fluid pressure comprising a variable displacement pump III which may be of any suitable construction and is shown as of the wellknown Waterbury type comprising a revolving cylinder barrel l2 having parallel cylinder bores within which pistons are reciprocated by means of a tilting box and socket ring assembly ll. Fluid is drawn into the cylinder bores from a return conduit l6 through an arcuate valve port and is delivered to an arcuate valve port I8 and pressure conduit 20. The quantity of fluid delivered is determined by the inclination of the tilting box I relative. to the main shaft 22, the position of the tilting box being controlled by a constant pressure regulating mechanism 24 comprising a spring-loaded plston 26 which is connected to a'tilting box operating stud 28 and operates to increase the displacement of the pump upon a decrease in pressure in the line 20 and to decrease the displacement of the pump upon an increase in pressure in the line 20.

The shaft 22 may be driven from a suitable prime mover, such as an electric motor 30. The conduits l6 and 20 are connected to a plurality of fluid motors 32 so thatthe motors are in parallel with the pump 10. Each of the motors grammatically at 34.

The construction of the motors and the controlmechanism incorporated in each is illustrated in Figs. 2 through 4. The revolving parts of the motor 32 may be similar to those of the pump Hi, the tilting box operating stud 38 extending vertically from the top thereof for controlling the displacement of the motor 32. The stud 36 is operated by a piston 38 slidably mounted in a sleeve 31 having end flanges 39 and 39'. Springs 40 and 4| are mounted in the sleeve 31 so that when the sleeve is moved to the right, as shown, the spring 4| engages the left end of piston 38 and spring 40 is free. When the sleeve 31 is moved to the left, the spring 40 engages the right end of piston 38 and spring 4| is free. A pump 43, of any suitable fixed displacement type, delivers fluid under pressure through either a conduit 44 or.a conduit 45, depending on the direction of rotation, and withdraws fluid from the other conduit. A shaft 46 of the motor projects into a valve plate casting 48 beyond the shaft bearings 58 to connect to the pump 43, whereby the pump is driven at the same speed and in thesame direction that the motor 32 operates.

The conduits 44 and 45 connect with cylinders 41 and 48 behind the flanges 39 and 39', from which communication may be established to the interior of sleeve 31 through openings 5| and 53. A by-pass conduit 52 connects the conduits 44 and 45 and is controlled by a manually adjustable throttle valve 54. By adjustment of the valve 54 the pressure developed by pump 43 at any speed may be varied. The pump 43, valve 54, piston 38 and springs 40 and 4| constitute a speed governing system whereby the stroke of the motor 32 may be regulated to maintain a piston 38.

substantially constant speed of the motor shaft.

For the purpose of concurrently controlling the volume of fluid supplied to the motor 32, a piston valve 56 is connected by a stem 58 to the The valve 56 has two piston heads 60 and 62 slidable in a bore 64. An inlet port 66 enters the bore 64 at a point intermediate the heads 68 and 62 and is connected to the high pressure conduit 20. Apair of delivery ports 68 and 18 enter the bore 64 adjacent the heads 60 and 62 and are connected by a passage 68 to communicate with a valve port 12. The ports 68 and 18 are so spaced that only one port can be uncovered at a time and are arranged so that the opening is proportional to the displacement of the valve 55. The opposite valve port I4 com municates by a passage 16 with the return conduit I6.

In order to limit the range of movement of piston 38 and valve. 56 to'either one side or the other side of mid-position and also to lock these members in mid-position, means is provided comprising a cam bar 18 (Fig. 4) which is mounted in a cavity 88. The cam bar 18 is rigidly secured to a shaft 82 mounted in the valve plate 48 and projecting from the top thereof. The cam bar 18 is provided with two oppositely facing cam surfaces 84 and 86 which may be projected through openings 88 and 80 into the bore 64 to engage the piston heads 68 and 62. In the position shown in the drawings the cam face 86 limits the movement of piston 38 to the left in Fig. 2 to a minimum displacement position just short of mid-position. When the cam bar 18 is rotated clockwise in Fig.- 4 through one half its range the piston heads 68 and 62 are held between the cam surfaces 84 and 86 and the piston 38 is retained in mid-position. "When'the cam bar is moved the full extent oi, its clockwise movement, the piston 38 is limited in movement to a minimum displacement position just short of mid-position but on the left-hand side thereof as seen in Fig. 2. The position of the cam' bar 18 is controlled by a hand lever 92 rigidly secured to the shaft 82 and having a spring-pressed detent 84 engageable in holes 86 for positive retention of the lever 82 in any of the three positions described.

In operation the prime mover 38 is started causing the pump Hi to deliver fluid to conduit 20. The quantity of fluid delivered is automatically varied to maintain a constant pressure in the conduit 28 by the pressure regulating mechanism 24. If it is desired to start one of the load devices 34, the lever 92 may be moved to one side or the other of mid-position and the throttle valve 54 partially closed. The cam bar I8 will hold the piston 38 and valve 56 in a position slightly off mid-position, as shown in the drawings. Fluid is thus permitted to pass through valve 56 from line 28 to valve port 12 and the motor 32 is caused to revolve driving its connected load device 34. The pump 43 being thus operated with motor 32, pressure will be developed in conduit 44, for example, causing the sleeve 31 to move to the right into the position illustrated in the drawings. The spring 4| is thus rendered effective to urge piston 38 to the right against the fluid pressure developed by pump 43 anddelivered through opening 5|. For a given setting of the throttle valve 54 the piston 38 and valve 56 will take up a position which is determined by the resisting torque load. Thus assuming the load to be heavy the motor will tend to slow down, or if starting will fail to come up to speed, so that the pressure developed in conduit 44 is low. Spring 4| is thus able to move piston 38 to the right, increasing the displacement of motor 32 and increasing the volume of fluid supplied thereto. The motor is then able to handle the greater load because, by its greater displacement, the leverage of the fluid on the shaft is increased. The speed is not decreased, however, because the valve 56 was opened by an amount corresponding to the increased displacement so that a greater volume of fluid is supplied to the motor, which volume is suflicient to make up for the increased volume requirements. Upon a decrease in load on the shaft 46, the opposite action takes place.

The motor thus tends to operate at a constant speed regardless of variations in load torque. The speed may be adjusted by varying the opening at throttle valve 54. Thus, if the valve is further closed, the same pressure will be built up in conduit 44 or 45 at a lower speed than before and if opened the pressure will not be built up sufllciently until a higher speed is reached. It will be understood, of course, that the speed of the motor is not maintained absolutely constantfor all loads. Due to the slight variation in pressure exerted by the spring 40 or 4| under different amounts of compression, the fluid pressure in the outlet of pump 43 which is required to balance the spring force at different positions of piston 38, varies correspondingly. This variation may be made as small as desired by proper selection of the springs 4| for force-deflection characteristics so that the variation in speed between light load and full load operation may be made as small a percentage of the average speed as may be desired.

The motor may be reversed by first opening the valve 54 fully to bring the motor to a stop or to a slow speed, and then shifting lever 82 to the opposite extreme position. The same action then takes place as that described above except the motor shaft turns in the opposite direction, the piston 38 and sleeve 31 operate on the lefthand side oi mid-position and pressure is built up in conduit 45.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a power transmission system the combination with a source of fluid under predetermined pressure a plurality of variable displacement fluid motors connected in'parallel with the source, an independent, variable torque load de-;

crease the displacement and to open the valve in response to a slight decrease in motor speed.

,2. In a power transmission system the combination with a source of fluid under predetermined pressure a plurality of variable displacement fluid motors connected in parallel with the source, an independent, variable torque load device connected to each fluid motor, and means associated with each motor for controlling the displacement thereof and for controlling the quantity of fluid supplied thereto in a manner to maintain the motor speed substantially constant under varying load torque, said means comprising a throttle valve and a displacement regulator, means for operating the valve and displacement regulator simultaneously to increase the displacement and to open the valve in response to a slight decrease in motor speed,'and adjusting means for varying the constant speed at which the motor is controlled by the first means.

3. In a power transmission system the combination with a source of fluid under predetermined pressure a plurality of variable displacement fluid motors connected in parallel with the source, an independent, variable torque load device connected to each fluid motor, and means associated with each motor for controlling the displacement thereof and for controlling the quantity of fluid supplied thereto in a manner -to maintain the motor speed substantially constant under varying load torque, said means comprising a throttle valve and a displacement regulator, and means including a fixed displace-' ment auxiliary pump driven by the motor and a fluid motor responsive to the delivery pressure of said auxiliary pump for operating the valve and displacement regulator to increase the displacement. and toopen the valve in response to a slight decrease in motor speed.

4. In a power transmission system the combination with a source of fluid under predetermined pressure a plurality of variable displacement fluid motors connected in parallel with the source, an independent; variable torque load device connected to each fluid motor, means associated with each motor for controlling the displacement thereof and for controlling the quantity of fluid supplied thereto in a manner to maintain the motor speed substantially constant under varying load torque, said means comprising a throttle valve and a displacement regulator, means. including a fixed displacement auxiliary pump driven bythe motor and a fluid motor responsive to the delivery pressure of said auxiliary pump for operating the valve and displacement regulator to increase the displacement and to open the valve in response to a slight decrease in motor speed, and adjusting means including a by-pass valve connected to the outlet of the auxiliary pump for varying the constant'speed at which the motor is controlled by the first means.

5. A fluid motor and control mechanism adapted to drive. a variable torque load at substantially constant speed when connected witha source of fluid at constant pressure comprising in combination a variable displacement fluid motor, and means for controlling the motor displacement and the quantity of fluid supplied to the motor, said means comprising a throttle valve and a displacement regulator, and means for operating the valve and displacement regulator simultaneously to increase the displacement and to open the valve in response to a slight decrease in motor speed.

6. A fluid motor and control mechanism adapted to drive a variable torque load at substantially constant speed when connected with a source of fluid at constant pressure comprising in combination a variable displacement fluid motor, means for controlling the motor displacement and the quantity of fluid supplied to the motor, said means comprising a throttle valve anda displacement regulator, means for operating the valve and displacement regulator simultaneously to increase the displacement and to open the valve in response to a slight decrease in motor speed, and adjusting means for varying the constant speed at which the motor is controlled.

7. A fluid motor and control mechanism adapted to drive a variable torque load at substantially constant'speed when connected with a source of fluid at constant pressure comprising in combination a variable displacement fluid motor, means for controlling the motor displacement and the quantity of fluid supplied to the motor, said means comprising a throttle'valve and a displacement regulator, and means including a fixed displacement auxiliary pump driven by the motor and a fluid motor responsive to the delivery pressure of said auxiliary pump for operating the valve and displacement regulator to increase the displacement and to open the valve in response to a slight decrease in moto speed.

8; A' fluid motor and control mechanism adapted to drive a variable torque load at substantially constant speed when connected with a source of fluid at constant pressure comprising in combination a variable displacement fluid motor, means for controlling the motor displacement and the quantity of fluid supplied ,to the motor,

said means comprising a throttle valve and a displacement regulator, means including a fixed displacement auxiliary pump driven by the motor and a fluid motor responsive to the delivery pressure of said auxiliary pump for operating the valve and displacement regulator to increase the displacement and to open the valve in response to a slight decrease in motor speed, and adjusting means including a by-passvalve connected to the outlet of the auxiliary pump for varying 'tain the motor speed substantially constant under varying load torque, said means comprising a throttle valve and a displacement regulator, and means for operating the valve and displacement regulator simultaneously to increase the displacement and to open the valve in response to a slight decrease in motor speed, and means for reversing the direction of rotation of the motor while maintaining the same connection to said source.

10. In a power transmission system the combination with a source of fluid under predetermined pressure a plurality of variable displacement fluid motors connected in parallel with the source, an independent, variable torque load device connected to each fluid motor, and means associated with each motor for controlling the displacement thereof and for controlling the quantity of fluid supplied thereto in a manner to maintain the motor speed substantially constant under varying load torque, said means comprising a throttle valve and a displacement regulator, means for operating the valve and displacement regulator to increase the displacement and to open the valve in response to a slight decrease in motor speed, and means normally preventing movement of the displacement controlling means into zero displacement position.

11. A fluid motor and control mechanism adapted to drive a variable torque load at substantially constant speed when connected with a source offluid at constant pressure comprising in combination a variable displacement fluid motor, means for controlling the motor displacement and the quantity of fluid supplied to the motor, said means comprising a throttle valve and a displacement regulator, and means for operating the valve and displacement regulator to increase the displacement and to open the valve in response to a slight decrease in motor speed, and means normally preventing movement of the displacement controlling means into zero displacement position.

12. In a power transmission system the combination with a source of fluid under predetermined pressure a plurality of variable displacement fluid motors connected in parallel with the vice connected to each fluid motor, means associated with each motor for controlling the displacement thereof and for controlling the quantity of fluid supplied thereto in a manner to maintain the motor speed substantially constant under varying load torque, said means comprising a throttle valve and a displacement regulator, and means for operating the valve and displacement regulator to increase the displacement and to open the valve in response to a slight decrease in motor speed, and means normally preventing movement of the displacement controlling means into zero displacement position and operable selectively to limit the range of movement of the displacement controlling means to one or the other side of zero displacement position.

13. A fluid motor and control mechanism adapted to drivea variable torque load at substantially constant speed when connected with a source of fluid at constant pressure comprising in combination a variable displacement fluid motor, means for controlling the motor displacement and the quantity of fluid supplied to the motor, said means comprising a throttle valve and a displacement regulator, andmeans for op crating the valve and displacement regulator to increase the displacement and to open the valve source, an independent, variable torque load deaaiaraa in response to a slight decrease in motor speed, and means normally preventing movement of the displacement controlling means into zero displacement position and operable selectively to limit the range of movement of the displacement controlling means to one or the other side of zero displacement position.

14. In a power transmission system the combination with a source of fluid under predetermined pressure a plurality of variable displacement fluid motors connected in parallel with the source, an independent, variable torque load device connected to each fluid motor, means associated with each motor for controlling the displacement thereof and for controlling the quantity of fluid supplied thereto in a manner to maintain the motor speed substantially constant under varying load torque, said means comprising-a throttle valve and a displacement regulator, and means for operating the valve and displacement regulator to increase the displacement and to open the valve in response to a slight decrease in motor speed, and means normally preventing movement of the displacement controlling means into zero displacement position and selectively operable to hold the displacement controlling means in zero displacement position for stopping the motor.

' ment of the displacement controlling means into zero displacement position, and selectively operable to hold the displacement controlling means in zero displacement position for stopping the motor.

16. In a power transmission system the combination with a source of fluid under predetermined pressure a plurality of variable displacement fluid motors connected-in parallel with the source, an independent, variable torque load device connected to each fluid motor, means associated with each motor for controlling the displacement thereof, means for controlling the quantity of fluid supplied thereto in a manner to maintain the motor speed substantially constant under varying load torque, said last two means being simultaneously operable, and means for reversing the direction of rotation of the motor while maintaining the same connection to said source.

17. A fluid motor and control mechanism adapted to drive a variable torque load at substantially constant speed when connected with a source of fluid at constant pressure comprising in combination a variable displacement fluid motor, means for controlling the motor displace-' ment, meansfor controlling the quantity of fluid supplied to the motor, said last two means being simultaneously operable and means normally preventing movement of the displacement controlling means into zero displacement position.

EDWIN L. ROSE. 

